In known electro-hydraulic control systems, each roof support along a longwall face is provided with an individual electronic control device with a microprocessor with all the individual control units being connected to one another and optionally to a central control station for transmission of data via a data transmission system. (See Gluckauf", 1981, pages 1155 to 1162; "Gluckauf", 1984, pages 135 to 140; "Gluckauf", 1986, pages 543 to 552; "Gluckauf", 1986, pages 1183 to 1187). The individual control units are provided with keyboards with which the various control processes (individual or sequence control at adjacent supports, sequential control with sliding supporting groups etc.) can be triggered. The intrinsically safe control systems preferably comprise a decentralised power supply system.
In known electro-hydraulic control systems, the construction and cabling costs are considerable owing to the plurality of supports normally used and the consequential plurality of electronic control units interconnected via the power supply and data transmission systems.
An object of the invention is to provide a data transmission/reception system which is simplified in construction and in which a relatively large number of control units, microcomputer-controlled transmitting and receiving stations can also be connected with more reasonable construction and cabling costs.